1. Field of the Invention
This invention is generally related to apparatus and method for automatically and continuously drilling, punching, perforating or otherwise producing openings of selected diameter and spacing in polymeric pipe or tube material such as used in underground drainage or air conditioning systems; and more particularly to a method and apparatus wherein a drill head receives an unperforated length of tubing and the drill head and tubing move in synchronization with one another between a tube receiving and tube discharging station during which time drills in the drill head are actuated to form openings in the length of tubing, whereupon the perforated length of tubing is discharged and the drill head returned to receive the next succeeding length of tubing.
2. Related Art
Apparatus for drilling, punching, perforating, or otherwise providing holes or openings of predetermined diameter and spacing in a workpiece are known. Orth U.S. Pat. Nos. 1,1044,564 and 1,101,879 disclose an apparatus wherein drill carriers for boring nail openings in the edge of flooring material are positioned along an oval conveyor belt. The drill carrier and work piece move together in unison as a result of spurs or dogs associated with the drill spindles being rotated by the advancing belt into gripping engagement with the flooring material.
Palmer U.S. Pat. No. 4,898,501 discloses apparatus wherein a continuous length of elastomeric gasket stock is brought into tangential engagement with the outer circumference of a drill wheel. As the stock is advanced, the wheel is rotated and radially arranged drilling units in the wheel are rotated into register with the stock and the stock drilled.
Apparatus for perforating axial sections of corrugated tubing is disclosed in U.S. Pat. No. 3,910,713 (Maroschak); and U.S. Pat. No. 4,219,293 (Licht). In each, and in a manner similar to Palmer, the corrugated tube section is positioned to be tangential to the outer circumference of a radially toothed drive wheel and radial teeth in the wheel engaging with corrugations in the tube section. As the wheel is rotated, the teeth engage with successive of the corrugations, causing the tube section to move and successive radially arranged drill units in the wheel to rotate into register with and drill the tube section.
U.S. Pat. Nos. 5,572,917; 5,385,073; 5,381,711; and 5,957,020, each issuing Truemner et al., disclose apparatus for perforating corrugated tubing, which apparatus includes an array of multiple feeder-cutter wheels that operate to drive tubing through the apparatus and concurrently perforate the tubing in the valley of its corrugations.
While believed suitable for their intended purposes, the apparatus disclosed herein above have disadvantages, such as being complex, expensive, not dependable, and possibly not capable of being modified to produce multiple openings in smooth-walled tubing, in a continuous, automatic manner, whether the tubing is single or multi-walled.
Heretofore the forming of multiple and/or uniform openings in both smooth-walled and multiple walled corrugated tubing has presented problems. The reason for this is believed to be that as the tube section is moved past a succession of drill spindles, the openings are not drilled exactly in synchronous relation to one another, thereby leading to splitting of the tube and possibly tool breakage. As a result, the part may have to be scrapped, the tool replaced and the production stopped.